• 한국안전학회지
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• 제38권2호
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• pp.1-7
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• 2023

Fiber-metal laminates (FMLs) and polymer matrix composites (PMCs) are formed in various ways. In particular, FMLs in which aluminum is laminated as a reinforced layer are widely used. Also, glass fiber-reinforced plastics (GFRPs) are generally applied as fiber laminates. The bonding interface layer between the aluminum and fiber laminate exhibits low strength when subjected to hot press fabrication in the event of delamination fracture at the interface. This study presents a simple method for strengthening the interface bonding between the aluminum metal and GFRP layer of FML composites. The surfaces of the aluminum interface layer are engraved with three kinds of patterns by using the laser machine before the hot press works. Furthermore, the effect of the laser patterns on the interfacial toughness is investigated. The interfacial toughness was evaluated by the energy release rate (G) using an asymmetric double cantilever bending specimen (ADCB). From the experimental results, it was shown that the strip type pattern (STP) has the most proper pattern shape in GFRP/Al FML composites. Therefore, this will be considered a useful method for the safety assessment of FML composite structures.

• 한국세라믹학회지
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• 제25권3호
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• pp.231-236
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• 1988

$Al_2O_3$ 기지에 미치는 2차상의 영향을 알아보기 위하여 SiC 입자를 5~20vol.% 분산시키고 소결조제로서 $TiO_2$ 또는 RY_2O_3$를 2.5wt.%첨가하여 180$0^{\circ}C$, $N_2$분위기 중에서 90분간 상압소결 하였다. SiC함량이 증가함에 따라 소결체의 밀도는 감소하였지만 기계적 물성은 증가하여 $Y_2O_3$를 소결조제로 첨가한 경우, 꺾임강도는 525MPa, 경도는 17.1GPa,파괴인성은 4.1 MPa.$m^{1/2}$ 정도의 최고값을 나타내었고 반면 $TiO_2$를 소결조제로 첨가한 경우 꺾임강도 285MPa , 경도 12.1GPa 정도의 값을 나타냈다. 그리고 이와 같은 기계적 물성의 증진은 주로 SiC의 복합화에 따른 균열의 편향과 $Al_2O_3$ 의 입자성장억제효과에 의한 것으로 밝혀졌다.

• Advanced Composite Materials
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• 제18권4호
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• pp.381-394
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• 2009

The kinetics of centrifugal infiltration of fibrous tubular preform is built theoretically, and simulations are conducted to study the effects of various casting conditions on infiltration kinetics and macrosegregation by combining with the energy, mass and kinetic equations. A similarity way is used to simplify the one-dimensional model and the parameter is ascertained by an iterative method. The results indicate that the increase of superheat, initial preform temperature, porosity tends to enlarge the remelting region and decrease copper solute concentration at the infiltration front. Higher angular velocity leads to smaller remelting region and solute concentration at the tip. The pressure in the infiltrated region increase significantly when the angular velocity is much higher, which requires a stronger preform. It is observed that the pressure distribution is mainly determined by the angular velocity, and the macrosegregation in the centrifugal casting is greatly dependent on the superheat of inlet metal matrix, initial temperature and porosity of the preform, and the angular velocity.

• 한국분말재료학회지
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• 제9권6호
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• pp.441-448
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• 2002

Dispersions of non-soluble ceramic particles in a metallic matrix can enhance the strength and heat resistance of materials. With the advent of mechanical alloying it became possible to put the theoretical concept into practice by incorporating very fine particles in a flirty uniform distribution into often oxidation- and corrosion- resistant metal matrices. e.g. superalloys. The present paper will give an overview about the mechanical alloying technique as a dry, high energy ball milling process for producing composite metal powders with a fine controlled microstructure. The common way is milling of a mixture of metallic and nonmetallic powders (e.g. oxides. carbides, nitrides, borides) in a high energy ball mill. The heavy mechanical deformation during milling causes also fracture of the ceramic particles to be distributed homogeneously by further milling. The mechanisms of the process are described. To obtain a homogeneous distribution of nano-sized dispersoids in a more ductile matrix (e.g. aluminium-or copper based alloys) a reaction milling is suitable. Dispersoid can be formed in a solid state reaction by introducing materials that react with the matrix either during milling or during a subsequent heat treatment. The pre-conditions for obtaining high quality materials, which require a homogeneous distribution of small dis-persoids, are: milling behaviour of the ductile phase (Al, Cu) will be improved by the additives (e.g. graphite), homogeneous introduction of the additives into the granules is possible and the additive reacts with the matrix or an alloying element to form hard particles that are inert with respect to the matrix also at elevated temperatures. The mechanism of the in-situ formation of dispersoids is described using copper-based alloys as an example. A comparison between the in-situ formation of dispersoids (TiC) in the copper matrix and the milling of Cu-TiC mixtures is given with respect to the microstructure and properties, obtained.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.139-142
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• 2002

This study presents a mathematical model predicting the stress-strain behavior of fiber reinforced (FMMCs) and fiber/particle reinforced metal matrix composites (F/P MMCs). MMCs were fabricated by squeeze casting method using Al2O3 short fiber and particle as reinforcement, and A356 aluminum alloy as matrix. The fiber/particle ratios of F/P MMCs were 2:1, 1:1, 1:2 with the total reinforcement volume fraction of 20 vol.%, and the FMMCs were reinforced with 10 vol,%, 15 vol. %, 20 vol. % of fibers. Tensile tests were conducted and compared with predictions which were derived using laminate analogy theory and multi-failure model of reinforcements. Results show that the tensile strength of FMMCs with 10 vol.% of fiber was well matched with prediction, and as the fiber volume increases, predictions become larger than experimental results. The difference between the prediction and experiment is considered to be a result of matrix allowance of fiber damage in tensile loading. As the fiber volume fraction in FMMCs increases, the fiber damage increases and so that the tensile strength is reduced. The strength of F/P MMCs approaches more closely to the prediction than FMMCs reinforced with 20 vol.% of fibers because F/P MMCs contains small quantity of fibers and thus has a positive effect in fiber strengthening.

• 한국결정성장학회지
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• 제15권6호
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• pp.269-275
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• 2005

Ni/Ni-aluminide//Ti/Ti-aluminide 경사기능 층상 복합재료를 박막 hot press법을 이용하여 제작하였다. NiAl과 $TiAl_3$ 금속간화합물 층이 자전고온합성반응을 통해 비교적 두껍게 형성되었고, 얇고 연속적인 $Ni_3Al$과 TiAl 층이 고상 확산을 통해 형성되었다. 파괴저항은 하중 방향이 crack arrester인 경우가 금속 층이 균열의 성장을 방해하기 때문에 crack divider 방향인 경우보다 높다. $Ni_3Al$과 NiAl 금속간화합물 층은 각각 벽개파괴와 입계파괴 거동을 보였고, $TiAl_3$층의 파괴 형태는 입내벽개파괴이었다. Ni/Ni-aluminide 층에서 관찰되는 기공과 금속 층과 금속간화합물 층의 미결합 부위가 낮은 파괴저항의 원인으로 판단된다. Acoustic emission (AE) 원파형 해석을 통해 제작된 복합재료의 파괴특성을 고찰하였다.

• 한국재료학회지
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• 제11권7호
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• pp.590-598
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• 2001

본 연구에서는 특별하게 고안된 In-situ VHP 제조 공정을 이용하여 상온에서 $500^{\circ}C$까지의 진공 열간 압축과 canning 작업 없이 $520^{\circ}C$에서 연속 압출옳 하여 Sicp/pure Al과 SiCp/2024Al MMCs를 제조하였다. 복합재료의 인장강도와 미세구조에 영향을 주는 SiC 입자크기, 체적률, 압출비에 대해서 조사하였다. 압출비 10:1의 경우에는 SiCp/pure Al과 SiCp/2024Al 복합재료 둘 다 건전한 외형과 SiCp의 일정한 분산을 가지면서 SiCp의 균열이 없는 좋은 미세 구조를 가지고 있었다. 그러나 압출비 16:1의 경우에는 체적률이 증가할수록 파괴된 SiC 입자의 수가 증가하였으며 2024Al 기지내의 복합재료와 순수한 Al 기지재 복합재료를 서로 비교하였다. 동일한 체적률과 압출비의 경우에는 SiCp의 크기가 작은 복합재료가 SiCp가 큰 복합재료보다 인장강도가 더 높았다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.376-379
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• 2004

The aim of this study is to prepare mixed Ni/Mg/Al/Cu/Ti powder in epoxy matrix with carbon fiber (NCF, MCF, ACF, CCF, TCF) conductive composite possessing eletromagnetic interference(EMI) shilding effectiveness(SE). A series if NCF/MCF/ACF/CCF/TCF composite were prepared by the hand lay up method. The various compositions of NCF/MCF/ACF/CCF/TCF were 10, 25, 50 percent by weight. The best EMI shilding effectiveness of all NCF/MCF/ACF is doout 40dB.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.827-831
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• 1997

Conductive veramic matrix composite(CMC) workpiece of TiC 33%/Al /sab 2/O /sab 3/ 66% Y /sab 2/ O /sab 3/ was machined by die sinking electrical discharge machining(EDM) according to different pulse duration and suty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operating conditions. The surface morphology was evaluated by surface roughness values and scanning electron microscopy(SEM) research. The more MRR was obtained according to increase pulse duration and duty factor. Also the maximum surface roughness(Rmax) of EDMed surface was slightly changed with increased pulse duration and duty factor. The SEM photographs of EDMed surface showed wide recast wide recast distribution region of melting materials in purse duration 0.130(ms) than 0.048(ms).

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.143-146
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• 2002

Mg alloy is the lightest material of structural materials and is noticed for lightweight automotive parts because of excellent castability, superior ductility and damping capacity than Al alloy. But Mg Alloy is poor corrosion resistance and high temperature creep properties. In this study, Mg Matrix Composites were fabricated by squeeze casting method to improve high temperature creep properties and damping capacity. Hybrid Mg composites reinforced with Alborex, graphite particle, and SiCp was improved creep properties and damping capacity compared with Mg alloy. Compared to the length ($9\mu\textrm{m}, 27\mu\textrm{m}, 45\mu\textrm{m} etc.$), Hybrid Mg composites reinforced with SiCp, one of the most superior of the length and Alborex were more superior than those reinforced with graphite particle and Alborex in mechanical properties, creep characteristics, and damping capacity, etc.